From b00dcb1b9d56a576bdd675b1c52e6c3ce6f1185e Mon Sep 17 00:00:00 2001
From: Eugene Yokota <eed3si9n@gmail.com>
Date: Fri, 16 Nov 2018 23:06:36 -0800
Subject: [PATCH] Fix task progress blank line behavior

Run readyLog lazily.
---
 .../scala/sbt/internal/TaskProgress.scala     | 20 +++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/main/src/main/scala/sbt/internal/TaskProgress.scala b/main/src/main/scala/sbt/internal/TaskProgress.scala
index 641f3a932..04e792510 100644
--- a/main/src/main/scala/sbt/internal/TaskProgress.scala
+++ b/main/src/main/scala/sbt/internal/TaskProgress.scala
@@ -29,6 +29,7 @@ private[sbt] final class TaskProgress(currentRef: ProjectRef) extends ExecutePro
   private[this] val calledBy = new ConcurrentHashMap[Task[_], Task[_]]
   private[this] val anonOwners = new ConcurrentHashMap[Task[_], Task[_]]
   private[this] val isReady = new AtomicBoolean(false)
+  private[this] val isLogReady = new AtomicBoolean(false)
   private[this] val isAllCompleted = new AtomicBoolean(false)
 
   override def initial: Unit = ()
@@ -75,7 +76,6 @@ private[sbt] final class TaskProgress(currentRef: ProjectRef) extends ExecutePro
         Thread.sleep(500)
       }
     }
-    readyLog()
     while (!isAllCompleted.get) {
       blocking {
         report()
@@ -86,13 +86,16 @@ private[sbt] final class TaskProgress(currentRef: ProjectRef) extends ExecutePro
 
   private[this] val console = ConsoleOut.systemOut
   private[this] def readyLog(): Unit = {
-    console.println("")
-    console.println("")
-    console.println("")
-    console.println("")
-    console.println("")
-    console.println("")
-    console.print(CursorUp5)
+    if (isLogReady.get) ()
+    else {
+      console.println("")
+      console.println("")
+      console.println("")
+      console.println("")
+      console.println("")
+      console.print(CursorUp5)
+      isLogReady.set(true)
+    }
   }
 
   private[this] val stopReportTask =
@@ -100,6 +103,7 @@ private[sbt] final class TaskProgress(currentRef: ProjectRef) extends ExecutePro
   private[this] def report(): Unit = console.lockObject.synchronized {
     val currentTasks = activeTasks.asScala.toList
     def report0: Unit = {
+      readyLog()
       console.print(s"$CursorDown1")
       currentTasks foreach {
         case (task, start) =>